Motorcyclists who use their bikes in off-road activities often find that dirt and debris accumulate on the lens surface of the goggle. This substantially reduces visibility and makes safe operation difficult. Accumulation of debris on the lens surface is a particular problem in activities such as motocrosses and hill climbs. The decreased visibility due to debris, together with the high speed of these events, can produce dangerous operating conditions.
One known solution to this problem, as disclosed in U.S. Pat. No. 4,428,081, is provided by a goggle in which a webbing of transparent material is fed over the goggle lens by means of rollers mounted at the opposite side edges of the goggle frame. When the segment of transparent webbing overlying the lens becomes dirty, the wearer pulls a cord to cause a fresh segment of the transparent webbing to be pulled across the lens. This solution requires an auxiliary mechanical feed mechanism, resulting in additional weight and complexity.
One solution that avoids the need for additional mechanic systems, as disclosed in U.S. Pat. No. 3,945,044, is tear-off transparent lenses. These tear-off lenses comprise individual, thin pieces of transparent plastic material that have the general shape of the goggle lens and which have tabs around their peripheral edges. A plurality of the transparent lenses may be overlaid on the goggle lens by inserting tabs between the lens and the flexible lens frame. When vision is obscured due to accumulation of debris, the wearer can reach up with one hand and tear away the outer tear-off lens. The dirty transparency is discarded and the wearer has a clear view through the lens and remaining unsoiled transparencies.
One principal drawback of the foregoing arrangement is that the transparencies are attached to the lens only by the tabs. In addition, the lenses must be individually mounted.
U.S. Pat. No. 4,455,689 discloses another type of removable transparency. In this patent, a specially configured bracket is inserted through the strap slot on one side of the goggle frame. A plurality of transparencies are then individually installed over the lens. Peripheral tabs on the lens-shaped portion of each transparency are inserted between the lens and the goggle frame. A retaining pin extending from the bracket is forced through a small hole formed in the inner region of an elongated member which extends from one end of the transparency. The elongated member of the transparency is folded back on itself so that the retaining pin extends through a large opening in the outer end of the elongated member. Successive transparencies are similarly mounted. The elongated member of the outermost transparency is not folded but is left free to be grasped with one hand so that the soiled transparency can be torn away from the goggle frame. The elongated member of the outermost transparency that has just been exposed will then automatically extend.
One disadvantage with this type of configuration is that the transparencies must be individually mounted over the lens. The considerable time and effort required to individually position and mount the transparencies can pose a significant drawback if the transparencies have to be mounted just prior to, or during, a race. In addition, individual transparencies are prone to damage due to scratching, for example, and can easily become soiled.
Another type of goggle having a tear off lens, identified as being marketed under the trademark Oakley, is discussed at Column 1, lines 63 et seq. of U.S. Pat. No. 4,455,689. In this goggle, an attachment element with a small round head projects outwardly from the goggle lens adjacent to one side thereof. A plurality of transparencies, each of which has an elongated member which extends beyond the left side edge thereof when viewed from the wearer's perspective, are individually mounted over the lens. The elongated members have a large circular hole adjacent to their outer end and a small hole which tightly fits over the rounded portion of the attachment element. Each of the transparencies has insertion tabs around the peripheral side edges thereof. The transparencies are mounted individually in a manner similar to that described with respect to the goggle disclosed in U.S. Pat. No. 4,455,689, by inserting the tabs between the lens and the lens frame and folding over the elongated portion.
It would therefore be desirable to provide transparencies which can be rapidly mounted on the goggle lens and to minimize the breakage loss associated with individual loose transparencies.